Electrochemical machining (ECM) is a non-traditional machining process that removes metal by electrolysis rather than mechanical forces. In ECM, a tool acts as a cathode and the workpiece as an anode, and an electric current is passed through an electrolyte in the gap between them, chemically dissolving metal from the workpiece. ECM can machine hard metals and complex shapes more accurately than traditional machining. It provides a smooth surface finish with no mechanical forces or heat affecting the workpiece material. However, ECM requires an electrolyte solution, specialized equipment, and produces chemical waste, making it more expensive and less environmentally friendly than other processes.

1. ELECTRO CHEMICAL
MACHINING PROCESS
D.PALANI KUMAR,
Assistant Prof. / Mech. Engg.,
Kamaraj College of Engg. & Tech.
Virudhunagar.

2. INTRODUCTION
• ECM is one of the recent and most useful
machining process.
• In this process, electrolysis method is
used to remove the metal from the
workpiece.
• It is best suited for the metals and alloys
which are difficult to be machined by
mechanical machining process.

3. What is ECM ?
• Electrochemical machining (ECM) is a
method of removing metal particules by an
electrochemical process instead of
standard machining methods.
• It gives a new perspective to machining
process and being an initiator of new
tecnologies. (Example: MECM)

4. Equipment
The electrochemical machining system has
the following modules:
• Power supply
• Electrolyte filtration and delivery system
• Tool feed system
• Working tank

5. POWER SUPPLY
• The applied current 50-40,000 A
• The voltage must be 5-30V D.C.
• The current density of this process is
generally high (20-300 A/𝑐𝑚2
).

6. Electrolyte Circulation System
• The entering pressure must be between
0.15 and 3 Mpa.
• The electrolyte system must include a
strong pump.
• The electrolyte is stored in a tank
• System also includes a filter, sludge
• removal system, and treatment units.

7. Control System
• Control parameters include:
*Voltage
*Inlet and outlet pressure of electrolyte
*Temperature of electrolyte.
The current is dependent on the above
parameters and the feed rate.

8. CONSTRUCTION
• It consists of workpiece, tool, servo motor
for controlling tool feed, D.C power supply,
electrolyte, pump, motor for pump, filter for
incoming electrolyte and reservoir for
electrolyte.
• A shaped tool (electrode) is used in this
process, which is connected to negative
terminals (cathode) and the workpiece is
connected to positive terminals (anode).

10. • The tool used in this process should be
made up of the material which have
enough thermal and electrical conductivity,
high chemical resistance to electrolyte and
adequate stiffness and machinability.
• Widely used tool materials are stainless
steel titanium, brass and copper.
• Tool is of hollow and the electrolyte is
circulated between the work and the tool.

11. Cont..
• Most widely used electrolyte in this
process is sodium nitrate solution.
• NaCl solution in water is a good alternative
but it is more corrosiveness.
• Other chemicals like sodium hydroxide,
sodium sulphate, sodium flouride,
potassium nitrate and potassium chloride.
• Servo motor is used for controlling the tool
feed and the filter is used to remove the
dust particles from the electrolytic fluid.

12. ECM

13. WORKING
• The tool and the workpiece
are held close to each other
with a very small gap (of
0.05 to 0.5mm) between
them by using a servo
motor.
• The electrolyte from the
reservoir is pumped at high
pressure and flows through
the gap between the
workpiece and the tool at a
velocity (of 30 to 60m/s).

14. WORKING
• A D.C voltage about 5-30 volts
is applied between the tool
and the work piece.
• Due to the applied voltage the
current flows through the
electrolyte with +ve charged
ions and –ve charged ions.
• The +ve charged ions moves
towards the tool (cathode)
while –ve ions moves towards
the workpiece (anode).
• The electro chemical reaction
takes place due to the flow of
ions and it causes the removal
of metal from the workpiece.

15. ANALYSIS OF MATERIAL
REMOVAL
• Electrolysis:
–D.C voltage of about 5-30V is applied
between the tool and work piece.
–So the current in water flows through the
electrolyte (solution of NaCl) with
charged ions.
–Many chemical reactions occurs at the
cathode and the anode.

17. Cont..
The following reaction are possible at cathode(tool)
Na+ + e- =Na
Na + H2O= Na(OH) + H+
2H+ + 2e- =H2 (Hydrogen evolution)
The following reaction occurs at cathode(Iron work
piece)
Fe↔Fe+++2e-
Fe+++2Cl-↔FeCl2
Fe+++2(OH)-↔Fe(OH)2
FeCl2 +2(OH)↔Fe(OH)2+2Cl-

18. Cont..
• According to Faraday’s first and second law
W=
𝐸𝐼𝑡
𝐹
W=mass of ions dissolved in
kg.ions
E=equivalent weight of a substance
dissolved
I=current flowing through the
electrolyte
t=time in sec
F=faraday’s constant=26.8Amp.hr

19. Material removal rate
MRR=
𝑊
𝐴ρ𝑡
m/s
Sub W equation
MRR=
𝐸𝐼
𝐹𝐴ρ
m/s
Feed rate of electrode
f=
𝑉
𝜌 𝑠ℎ
𝐸
𝐹𝜌
A=machined area
V=machine voltage
h=tool work gap

20. Tool material
• Since the tool has no contact with the work piece, there
is no tool wear. So any material that is good conductor of
electricity can be used as tool material
• Most commonly used tool materials are copper, brass,
titanium, copper tungsten and stainless steel when the
electrolyte is made of sodium or potassium
Properties Copper Brass Stainless steel Copper tungsten
Electrical resistivity 1 4 53 8
Stiffness 1.60 1 1.9 2.2
Machinability 6 8 2.5 1.8
Thermal conductivity 25 7.5 1 10

21. Electrolyte
Low electrolyte temperature results in low
MRR and high temperature leads to
vaporization of the electrolyte, so it’s
maintained around 35ᵒC to 65ᵒC
Material Electrolyte
Iron based alloys 20% of NaCl solution in water
Ni based alloys Mixture of brine and H2SO4
TI based alloys 10% of HF+10%of HCl+10%HNO3
Co-Cr based alloys NaCl
WC based alloys Strong alkaline solution

22. Surface finishing
Factors govern the accuracy of the parts produced
by ECM
Machining voltage
Tool feed rate
Temperature of electrolyte
Concentration of electrolyte
The surface finish in ECM process is of the order
0.2-0.8 micron with tolerance of 0.005mm depending
on work material and the electrolyte used .

23. Process Parameters
• Power Supply
• Type direct current
• Voltage 2 to 35 V
• Current 50 to 40,000 A
• Current density 0.1 A/mm2 to 5 A/mm2
• Electrolyte
• Material NaCl and NaNO3
• Temperature 20oC – 50oC
• Flow rate 20 lpm per 100 A current
• Pressure 0.5 to 20 bar
• Dilution 100 g/l to 500 g/l
• Working gap 0.1 mm to 2 mm
• Overcut 0.2 mm to 3 mm
• Feed rate 0.5 mm/min to 15 mm/min
• Electrode material Copper, brass, bronze
• Surface roughness, Ra 0.2 to 1.5 μm

24. 4/21/2017
ECM Vs EDM Vs CNC
TABLE Machining Characteristics of EDM and ECM
PROCESS MRR TOLERANCE SURFACE FINISH DAMAGE DEPTH POWER
mm3
/min micron micron micron watts
ECM 15,000 50 0.1-2.5 5 100,000
EDM 800 15 0.2-1.2 125 2700
CNC 50,000 50 0.5-5 25 3000
Note: MRR = metal removal rate; tolerance = tolerance maintained; surface finish =
surface finish required; damage depth = depth of surface damage; ECM =
electrochemical machining; EDM = electro-discharge machining; CNC = computer
numerical control machining.

25. Advantages
• No mechanical force
• There is no cutting forces therefore
clamping is not required except for
controlled motion of the work piece.
There is no heat affected zone.
• Very accurate.
• Relatively fast
• Can machine harder metals than the tool.

26. Cont..
• No material corrosion
• Provides smooth surfaces
• No need of harder material that is used in
processing.
• More sensitive and repeatable
• Provides of processing complex
geometries

27. Disadvantages
• Solution usage
• Pump,tank, pipe, filter and sink usage.
• Keeping the solution conductivity constant.
• More expensive than conventional
machining.
• Need more area for installation.
• Electrolytes may destroy the equipment.
• Not environmentally friendly (sludge and
other waste)
• High energy consumption.

28. Cont..
• The effect of the toxic gases and aerosols
produced in the course of ECM.
• Chemical attack by electrolytes.
• The risk of an electric shock.
• The danger of a burn in the case of a short circuit
between the positive and negative leads. .
• Mechanical factors.
• The danger of a fire damp explosion.
• The effects of the electromagnetic field.
• Material has to be electrically conductive

29. Applications
• The most common application of ECM is high
accuracy duplication. Because there is no
tool wear, it can be used repeatedly with a
high degree of accuracy.
• It is also used to make cavities and holes in
various products.
• It is commonly used on thin walled, easily
deformable and brittle material because they
would probably develop cracks with
conventional machining.

30. Applications in industries
• Applications are valid for highly sensitive
working areas like; electronic, air and
space industries.
• It has also contains many benefices that in
great industries like telecommunication,
automotive and defence industries.

31. Economics
• The process is economical when a large
number of complex identical products need to
be made (at least 50 units)
• Several tools could be connected to a
cassette to make many cavities
simultaneously. (i.e.cylinder cavities in
engines)
• Large cavities are more economical on ECM
and can be processed in 1/10 the time of
EDM.

32. Products
• The two most common products of ECM are
turbine/compressor blades and rifle barrels. Each of
those parts require machining of extremely hard
metals with certain mechanical specifications
• Some of these mechanical characteristics achieved by
ECM are:
Stress free grooves.
*Any groove geometry.
*Any conductive metal can be machined.
*Repeatable accuracy of 0.0005”.
*High surface finish.
*Fast cycle time.

33. Future
• Being a developing machining system;
provides a new tecniqual expertise areas
• With these developments;
electrochemical machining system found a
better condition to work in micro sizes
called MECM

34. Conclusion
• With eliminating the disadvantages,ECM
will provide a good efficiency and recycling
in machining processes
• It provides a faster and accurate system
for metal machining processes.
• It is an iniatior of newer techniques that
could be beneficial for industries.
• Also provides faster and good quality
works than conventional methods

35. THANK YOUTHANK YOU